What’s Certbot?

Certbot is a free, open-source software tool for automatically using Let’s Encrypt certificates on manually-administrated websites to enable HTTPS.

Wildcard certificates

Let’s Encrypt supports wildcard certificate via ACMEv2 using the DNS-01 challenge.

It is necessary to add a TXT record specified by Certbot to the DNS server.

Caution: As it is necessary to update Let’s Encrypt’s certificate every 90 days, a new TXT record is required at every renewal.

Step 1: Run command

certbot certonly --manual --preferred-challenges dns --server https://acme-v02.api.letsencrypt.org/directory --manual-public-ip-logging-ok -d '*.<your.domain>' -d <your.domain>

Step 2: Update DNS TXT record

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator manual, Installer None
Obtaining a new certificate
Performing the following challenges:
dns-01 challenge for <your.domain>

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Please deploy a DNS TXT record under the name
_acme-challenge.<your.domain> with the following value:

<acme-challenge-value>

Before continuing, verify the record is deployed.
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Press Enter to Continue

After a successful verification

Waiting for verification...
Cleaning up challenges

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/<your.domain>/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/<your.domain>/privkey.pem
   Your cert will expire on 2019-09-03. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"
 - If you like Certbot, please consider supporting our work by:

   Donating to ISRG / Let's Encrypt:   https://letsencrypt.org/donate
   Donating to EFF:                    https://eff.org/donate-le